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Drakkheim
01-25-2003, 07:12 PM
Ok, I've been working on making a believable glass material and a trying to figure out a way to avoid total internal reflection
(for a nice description of it check here (http://users.ipfw.edu/masters/Graphics/AM/Refraction.html)

What AM does is in places where Total internal reflection occur it simply fills in with the camera background color. So in your render you often get little blocks of color that don't match the scene you're building. Sometimes you can tweak the camera setting to make it work... sometimes you can't.

Anyway here's the image I came up with:
all 100% procedural textures.
The camera backgroind is a nice lime green so any TIR should show up splendidly...
If you want the project you can download it here. (http://www.drakkheim.com/software/)

C&C anyone?

Cosmics
01-26-2003, 12:14 AM
Hey that looks amazing despite the reflection problem and the pixelated edges
i have an idea, set the camera background to a rotoscope of the same image -- then maybe the TIR will look something like its supposed to.
Either way, beatiful scene, love the liquid

nerrazzi
01-26-2003, 03:07 AM
Nice work!

Raist3d
01-26-2003, 11:58 AM
Just to compare render quality I decided to try to recreate the same scene in Carrara's Studio demo...

First image is with pure raytracing (it has hybrid modes) and best AA, along with 12 rays depth:

http://members.cox.net/raisth/carrara/caustics/Carrara1.jpg


Second image is enabling best AA *and* best global illumination & caustics:

http://members.cox.net/raisth/carrara/caustics/Carrara2.jpg

The first took about 2-3 minutes on my 1.8 Ghz P4-M laptop.

The second took about 1 hour and 3 minutes *but* I was downloading e-mail and web surfing while doing it. Carrara didn't crash on me (it's the demo also) and it chugged along fine.

It would probably have taken like 5-10 minutes less if I left the computer alone.

Keep in mind both pictures are jpeg....

Raist3d
01-26-2003, 12:00 PM
.. ignore the cheesey procedural wood :D

Needed to find the right wood, but didn't bother.

Drakkheim
01-26-2003, 06:30 PM
so the first one toke 2-3 min in carerra...
It took 25 min in am... and mine is still full of nasty things that didnt antialias.

Anyone else have an oppertunity to recreate this in other renderers? I'd like to see how they do.

_drakk

HellBorn
01-26-2003, 09:19 PM
Raist3d, any chance you have this as an .obj model or something.
As Drakkheim said. It could be nice to get some render results from other applications.

walasek
01-26-2003, 09:25 PM
Hell use my AM->obj exporter (although you will have to redo the materials since that isn't supported yet)...

Raist3d
01-26-2003, 10:47 PM
Originally posted by Drakkheim
so the first one toke 2-3 min in carerra...
It took 25 min in am... and mine is still full of nasty things that didnt antialias.

Anyone else have an oppertunity to recreate this in other renderers? I'd like to see how they do.

_drakk

Dark, I would expect A:M to be slower but to make a fair comparison, I would like to know what cpu, speed, and how much ram your machine has.

Raist3d
01-26-2003, 10:52 PM
Originally posted by HellBorn
Raist3d, any chance you have this as an .obj model or something.
As Drakkheim said. It could be nice to get some render results from other applications.

Unfortunately no becuase I am using Carrara's Studio 2.0 demo and I can't save nor export.

In fact, I worked on that project a couple of hours to get the scene & look like Dark did in A:M and it was a "one way ticket" because I could not save the scene.

Actually I couldn't even save the rendered image, so what I did was to screen capture it and crop it using Paint Shop Pro... so I could get the image :-) (Sorry Antoine :-) ).

The cool thing I find about Carrara is that if you are a Photoshop lover, it can export a lot of information about the image in separate files (or layers?) about surface normals, light, etc. which then you can use with Photoshop for nice touch ups and composition.

Drakkheim
01-26-2003, 11:20 PM
running 1ghz athlon
win 2k professional
512 mb of ram
gforce 4400 (not that it impacts render speed)
and i dont run other apps while running A:M.

-Drakk

Raist3d
01-26-2003, 11:30 PM
Originally posted by Drakkheim
running 1ghz athlon
win 2k professional
512 mb of ram
gforce 4400 (not that it impacts render speed)
and i dont run other apps while running A:M.

-Drakk

Drakk, first sorry for calling you Dark:D

Ok, according to my own estimates your Athlon should perform like a P4 @ 1.3-1.5 Ghz I guess. If we take this into account (I also have 512 megs ram), and I did not run anything else when I made the first picture then we get:

(let's assume worst case for Carrara, which would be your Athlon = 1.3Ghz p4)

(1.8 Ghz P4 - 1.3 Ghz ) / 1.8Ghz P4 * 100 = roughly 28% slower

So if it took me say 2 minutes and 30 secs that would be = 2 * 60 + 30 = 150 secs

150 seconds of P4 @ 1.8Ghz * 1.28 = 192 seconds = 3 minutes and 22 seconds

So now we get A:M took 25 minutes / 3.36 minutes = 7.44 times Carrara is as fast as A:M (or 6.44 times faster)

yay!

To be 100% accurate, if you notice very very carefully on the glass cup on the left, you can see a bit of "polygonization" or polygon edges, but you can also increase the fidelity of spline objects (which is what I used) to make that go away. That would probably have added 10-12 seconds to the first render, and probably 2-5 minutes to the second one.

If you were using bitmaps for the textures of wood, then it might be faster for Carrara to have done the same as the wood was being generated procedurally.

Drakkheim
01-27-2003, 01:35 AM
Hey Raist, thanks for doing the math :)

Granted the procedural texture im using is a bit more complex and also has a bump version attributed to it, so that should also account for a little bit of the speed diference (but not a whole lot though)
So, yeah, the AM renderer turns out is painfully slow doing transparency..
Anyone out there willing to recreate this in lightwave 7+ just to satisfy my curiosity?

[edit]
I just noticed that in my image in the upper Right hand corner of the image (behind the glass intersecting the glass' shadow) there seems to be a dark triangular area, It isnt a shadow and I dont have any way to account for it... Anyone have any idea what caused it?

-Drakk

p.s. dont worry bout the Dark/Drakk thing.. i get it all the time :cool:

Raist3d
01-27-2003, 02:54 AM
Originally posted by Drakkheim


[stuff deleted]

[edit]
I just noticed that in my image in the upper Right hand corner of the image (behind the glass intersecting the glass' shadow) there seems to be a dark triangular area, It isnt a shadow and I dont have any way to account for it... Anyone have any idea what caused it?

-Drakk

p.s. dont worry bout the Dark/Drakk thing.. i get it all the time :cool:

About doing the math: you are welcome!

About the dark triangle: I originally noticed it too but chalked it up to be "part of some weird shadow.."" Hmmm..

- Raist

Hookflash
01-27-2003, 03:24 AM
Keep in mind that the Carrara 2 renderer is known for having very good speed & quality. Still, 7x faster is... well... Alot faster;) Maybe you should send the test result to Hash?

Squeakypics
01-27-2003, 05:00 PM
There is bits about the AM render I like but I didn't realise how bad it is compared to just about everything else. Those edge artifacts! - very poor.

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